Methods of corrosion resistance test for metallic coatings
Can be used to test the relative resistance to corrosion of electro-plated coatings, when exposed to different corrosive atmospheres, as follows:
Test specimens are placed in an enclosed chamber and exposed to a continuous indirect spray of neutral (pH 6.5 to 7.2) salt water solution, which falls-out on to the specimens at a rate of 1.0 to 2.0ml/80cm²/hour, in a chamber temperature of +35C. This climate is maintained under constant steady state conditions. The test duration is variable.
This test is also referred to as an NSS test
Test specimens are placed in an enclosed chamber and exposed to a continuous indirect spray of salt water solution, acidified (pH 3.1to 3.3) by the addition of acetic acid, which falls-out on to the specimens at a rate of 1.0 to 2.0ml/80cm²/hour, in a chamber temperature of +35C. This climate is maintained under constant steady state conditions. The test duration is variable.
This test is also referred to as an ASS test
Test specimens are placed in an enclosed chamber and exposed to a continuous indirect spray of salt water solution, with copper chloride added and acidified (pH 3.0 to 3.2) by the addition of acetic acid, which falls-out on to the specimens at a rate of 1.0 to 2.0ml/80cm²/hour, in a chamber temperature of +50C. This climate is maintained under constant steady state conditions. The test duration is variable.
This test is also referred to as a CASS test
Test specimens are coated with Corrodkote mud, which is applied to the surface of the samples and allowed to dry. Then the samples are placed in a controlled climate of +38C and 80 to 90%RH (non condensing) and allowed to stand for 16 hours (1 cycle). For further cycles the samples are cleaned and fresh Corrodkote is applied.
Test specimens are exposed to a controlled climate of +40C and 90%RH and SO2 gas in a concentration of either 25ppm or 1000ppm.
Chamber volumes of less than 200 Litres are not permitted by JIS H 8502.
